Take a reference rather than ownership

Author: dralley

src/writer.rs

@@ -349,7 +349,7 @@ impl<'a, W: Write> ElementWriter<'a, W> {
     #[cfg(feature = "serialize")]
     pub fn write_serializable_content<T: Serialize>(
         self,
-        content: T,
+        content: &T,
     ) -> std::result::Result<&'a mut Writer<W>, DeError> {
         use crate::se::Serializer;
 
@@ -704,7 +704,7 @@ mod indentation {
             .create_element("paired")
             .with_attribute(("attr1", "value1"))
             .with_attribute(("attr2", "value2"))
-            .write_serializable_content(content)
+            .write_serializable_content(&content)
             .expect("failure");
 
         assert_eq!(